21553473 has 8 divisors (see below), whose sum is σ = 28764000. Its totient is φ = 14355968.

The previous prime is 21553459. The next prime is 21553481. The reversal of 21553473 is 37435512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21553473 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21553473.

It is not an unprimeable number, because it can be changed into a prime (21553403) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1678 + ... + 6776.

It is an arithmetic number, because the mean of its divisors is an integer number (3595500).

Almost surely, 2^21553473 is an apocalyptic number.

It is an amenable number.

21553473 is a deficient number, since it is larger than the sum of its proper divisors (7210527).

21553473 is a wasteful number, since it uses less digits than its factorization.

21553473 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6511.

The product of its digits is 12600, while the sum is 30.

The square root of 21553473 is about 4642.5718088146. The cubic root of 21553473 is about 278.2952240444.

Adding to 21553473 its reverse (37435512), we get a palindrome (58988985).

The spelling of 21553473 in words is "twenty-one million, five hundred fifty-three thousand, four hundred seventy-three".